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Optimized TES microcalorimeters with 14 eV energy resolution at 30 keV for $$gamma$$-ray measurements of the $$^{229}$$Th isomer

村松 はるか*; 林 佑*; 湯浅 直樹*; 紺野 良平*; 山口 敦史*; 満田 和久*; 山崎 典子*; 前畑 京介*; 菊永 英寿*; 滝本 美咲; et al.

Journal of Low Temperature Physics, 200(5-6), p.452 - 460, 2020/09

 被引用回数:0 パーセンタイル:0(Physics, Applied)

We have developed a four-pixel array of superconducting transition-edge sensors with gold absorbers for the detection of a 29.2 keV $$gamma$$-ray doublet decay from $$^{229}$$Th. To identify the decay, an energy resolution better than 20 eV full width at half maximum (FWHM) is needed. We measured an energy resolution of 14 eV FWHM for 26 keV $$gamma$$-ray decay from an $$^{241}$$Am isotope in combined data of three pixels. We describe the design and the performance of the devices and discuss the baseline correction method to compensate the variation in the baseline, which was observed during the evaluation of the performance using the $$^{241}$$Am isotope.


Non-basal dislocation nucleation site of solid solution magnesium alloy

染川 英俊*; Basha, D. A.*; Singh, A.*; 都留 智仁; 山口 正剛

Materials Transactions, 61(6), p.1172 - 1175, 2020/06

 被引用回数:13 パーセンタイル:70.93(Materials Science, Multidisciplinary)



Energy of the $$^{229}$$Th nuclear clock isomer determined by absolute $$gamma$$-ray energy difference

山口 敦史*; 村松 はるか*; 林 佑*; 湯浅 直樹*; 中村 圭佑; 滝本 美咲; 羽場 宏光*; 小無 健司*; 渡部 司*; 菊永 英寿*; et al.

Physical Review Letters, 123(22), p.222501_1 - 222501_6, 2019/11

 被引用回数:31 パーセンタイル:88.91(Physics, Multidisciplinary)

The low-lying isomeric state of $$^{229}$$Th provides unique opportunities for high-resolution laser spectroscopy of the atomic nucleus. We determine the energy of this isomeric state by measuring the absolute energy difference between two $$gamma$$-decays from the 29.2-keV second-excited state. A transition-edge sensor microcalorimeter was used to measure the absolute energy of the 29.2-keV $$gamma$$-ray with improved precision. Together with the cross-band transition energy (29.2 keV$$rightarrow$$ground) and the branching ratio of the 29.2-keV state measured in a recent study, the isomer energy was determined to be 8.30$$pm$$0.88 eV. Our result is in agreement with latest measurements based on different experimental techniques, which further confirms that the isomeric state of $$^{229}$$Th is in the laser-accessible vacuum ultraviolet range.


Spatial anisotropy of neutrons emitted from the $$^{56}$$Fe($$gamma$$, n)$$^{55}$$Fe reaction with a linearly polarized $$gamma$$-ray beam

早川 岳人; 静間 俊行; 宮本 修治*; 天野 将*; 武元 亮頼*; 山口 将志*; 堀川 賢*; 秋宗 秀俊*; 千葉 敏*; 緒方 一介*; et al.

Physical Review C, 93(4), p.044313_1 - 044313_4, 2016/04

 被引用回数:7 パーセンタイル:50.69(Physics, Nuclear)

ニュースバル放射光施設で、直線偏光したレーザーコンプトン散乱$$gamma$$線を用いて$$^{56}$$Fe($$gamma$$, n)$$^{55}$$Fe反応から放出された中性子の角度分布の非対称性を計測した。ビーム軸に対して90$$^{circ}$$の角度における、$$gamma$$線の直線偏光面と検出器の間の方位角$$phi$$に関する中性子の強度の角度分布を計測した。7つの角度で計測された中性子の強度は、理論的に予言された関数$$a$$+$$ b$$cos(2$$phi$$)でよく再現された。


${it In situ}$ three-dimensional X-ray reciprocal-space mapping of InGaAs multilayer structures grown on GaAs(001) by MBE

佐々木 拓生; 高橋 正光; 鈴木 秀俊*; 大下 祥雄*; 山口 真史*

Journal of Crystal Growth, 425, p.13 - 15, 2015/09

 被引用回数:3 パーセンタイル:30.17(Crystallography)

${it In situ}$ three-dimensional X-ray reciprocal space mapping (${it in situ}$ 3D-RSM) was employed for studying molecular beam epitaxial (MBE) growth of InGaAs multilayer structures on GaAs(001). Measuring the symmetric 004 diffraction allowed us to separately obtain film properties of individual layers and to track the real-time evolution of both residual strain and lattice tilting. In two- layer growth of InGaAs, significant plastic relaxation was observed during the upper layer growth, and its critical thickness was experimentally determined. At the same thickness, it was found that the direction of lattice tilting drastically changed. We discuss these features based on the Dunstan model and confirm that strain relaxation in the multilayer structure is induced by two kinds of dislocation motion (dislocation multiplication and the generation of dislocation half-loops).


Development of space solar sheet with inverted triple-junction cells

山口 洋司*; 伊地知 亮*; 鈴木 善之*; 大岡 幸代*; 島田 啓二*; 高橋 直*; 鷲尾 英俊*; 中村 一世*; 高本 達也*; 今泉 充*; et al.

Proceedings of 42nd IEEE Photovoltaic Specialists Conference (PVSC-42) (CD-ROM), p.2407 - 2411, 2015/06

In order to develop high efficiency space solar cells with flexible and light weight, InGaP/GaAs/Ge Inverted Triple Junction (IMM-3J) solar cells mounted on film type sheet (film type space solar sheet) and glass type sheet (glass type space solar sheets) were fabricated and their reliability was investigated. As a result, no significant change in their characteristics (less than 1 % change) was observed for both types of space solar sheets after reliability tests, such as (1) thermal cycling (-180 to +120 $$^{circ}$$C, 1000 cycles), (2) humidity and temperature (65 $$^{circ}$$C, humidity 90 %, 720h), (3) high temperature under vacuum condition (160 $$^{circ}$$C, less than 10$$^{-5}$$ Torr, 168h), and (4) high temperature (150 $$^{circ}$$C, 1000 h). Both type space solar sheets also showed high radiation resistance compared to current version of space 3J solar cells. Therefore, we can conclude that the space solar sheets have enough reliability in space environments.


Material design for magnesium alloys with high deformability

染川 英俊*; 山口 正剛; 大澤 嘉昭*; Singh, A.*; 板倉 充洋; 都留 智仁; 向井 敏司*

Philosophical Magazine, 95(8), p.869 - 885, 2015/02

 被引用回数:22 パーセンタイル:72.1(Materials Science, Multidisciplinary)



2D neutron diffraction imaging on an ammonite

社本 真一; 樹神 克明; 伊巻 正*; 中谷 健; 大下 英敏*; 金子 直勝*; 増子 献児*; 坂本 健作; 山口 憲司; 鈴谷 賢太郎; et al.

JPS Conference Proceedings (Internet), 1, p.014011_1 - 014011_5, 2014/03



Real-time observation of crystallographic tilting InGaAs layers on GaAs offcut substrates

西 俊明*; 佐々木 拓生; 池田 和磨*; 鈴木 秀俊*; 高橋 正光; 下村 憲一*; 小島 信晃*; 大下 祥雄*; 山口 真史*

AIP Conference Proceedings 1556, p.14 - 17, 2013/09

 被引用回数:0 パーセンタイル:0.01

${it In situ}$ X-ray reciprocal space mapping during In$$_{x}$$Ga$$_{1-x}$$As/GaAs(001) MBE growth is performed to investigate effects of substrate misorientations on crystallographic tilting. It was found that evolution of the crystallographic tilt for the InGaAs films is strongly dependent on both layer structures and substrate misorientations. We discuss these observations in terms of an asymmetric distribution of dislocations.


New result in the production and decay of an isotope, $$^{278}$$113 of the 113th element

森田 浩介*; 森本 幸司*; 加治 大哉*; 羽場 宏光*; 大関 和貴*; 工藤 祐生*; 住田 貴之*; 若林 泰生*; 米田 晃*; 田中 謙伍*; et al.

Journal of the Physical Society of Japan, 81(10), p.103201_1 - 103201_4, 2012/10

 被引用回数:161 パーセンタイル:97.31(Physics, Multidisciplinary)

113番元素である$$^{278}$$113を$$^{209}$$Bi標的に$$^{70}$$Znビームを照射する実験により合成した。観測したのは6連鎖の$$alpha$$崩壊で、そのうち連鎖の5番目と6番目は既知である$$^{262}$$Db及び$$^{258}$$Lrの崩壊エネルギーと崩壊時間と非常によく一致した。この意味するところは、その連鎖を構成する核種が$$^{278}$$113, $$^{274}$$Rg (Z=111), $$^{270}$$Mt (Z=109), $$^{266}$$Bh (Z=107), $$^{262}$$Db (Z=105)及び$$^{258}$$Lr (Z=103)であることを示している。本結果と2004年, 2007年に報告した結果と併せて、113番元素である$$^{278}$$113を曖昧さなく生成・同定したことを強く結論付ける結果となった。


Observation of in-plane asymmetric strain relaxation during crystal growth and growth interruption in InGaAs/GaAs(001)

佐々木 拓生*; 下村 憲一*; 鈴木 秀俊*; 高橋 正光; 神谷 格*; 大下 祥雄*; 山口 真史*

Japanese Journal of Applied Physics, 51(2), p.02BP01_1 - 02BP01_3, 2012/02

 被引用回数:2 パーセンタイル:9.11(Physics, Applied)

In-plane asymmetric strain relaxation in lattice-mismatched InGaAs/GaAs(001) heteroepitaxy is studied by ${it in situ}$ three-dimensional X-ray reciprocal space mapping. Repeating crystal growth and growth interruptions during measurements allows us to investigate whether the strain relaxation is limited at a certain thickness or saturated. We find that the degree of relaxation during growth interruption depends on both the film thickness and the in-plane directions. Significant lattice relaxation is observed in rapid relaxation regimes during interruption. This is a clear indication that relaxation is kinetically limited. In addition, relaxation along the [110] direction can saturate more readily than that along the [$${bar 1}$$10] direction. We discuss this result in terms of the interaction between orthogonally aligned dislocations.


Real-time structural analysis of compositionally graded InGaAs/GaAs(001) layers

佐々木 拓生*; 鈴木 秀俊*; 稲垣 充*; 池田 和磨*; 下村 憲一*; 高橋 正光; 神津 美和*; Hu, W.; 神谷 格*; 大下 祥雄*; et al.

IEEE Journal of Photovoltaics, 2(1), p.35 - 40, 2012/01

 被引用回数:5 パーセンタイル:22.98(Energy & Fuels)

Compositionally step-graded InGaAs/GaAs(001) buffers with overshooting (OS) layers were evaluated by several characterization techniques for higher efficiency metamorphic III-V multijunction solar cells. By high-resolution X-ray diffraction, we found that fully relaxed or tensile strained top layers can be obtained by choosing appropriate OS layer thickness. Moreover, from real-time structural analysis using ${it in situ}$ X-ray reciprocal space mapping (${it in situ}$ RSM), it was proved that the top layer is almost strained to the OS layers, and it is independent of the thicknesses of the OS layers. Dislocations in the vicinity of the OS layers were observed by transmission electron microscopy, and the validity of results of ${it in situ}$ RSM was confirmed from the viewpoint of misfit dislocation behavior. Finally, by photoluminescence measurements, we showed that tensile strained top layers may be suitable for the improvement of minority-carrier lifetime.


X-ray reciprocal space mapping of dislocation-mediated strain relaxation during InGaAs/GaAs(001) epitaxial growth

佐々木 拓生*; 鈴木 秀俊*; 高橋 正光; 大下 祥雄*; 神谷 格*; 山口 真史*

Journal of Applied Physics, 110(11), p.113502_1 - 113502_7, 2011/12

 被引用回数:12 パーセンタイル:47.26(Physics, Applied)

Dislocation-mediated strain relaxation during lattice-mismatched InGaAs/GaAs(001) heteroepitaxy was studied through ${it in situ}$ X-ray reciprocal space mapping. At the synchrotron radiation facility SPring-8, a hybrid system of molecular beam epitaxy and X-ray diffractometry with a two-dimensional detector enabled us to perform ${it in situ}$ reciprocal space mapping at high-speed and high-resolution. Using this experimental setup, the lattice constants, the diffraction broadenings along in-plane and out-of-plane directions, and the diffuse scattering were investigated. The strain relaxation processes were classified into four thickness ranges with different dislocation behavior. In addition, the existence of transition regimes between the thickness ranges was identified.


Growth temperature dependence of strain relaxation during InGaAs/GaAs(0 0 1) heteroepitaxy

佐々木 拓生*; 鈴木 秀俊*; 崔 炳久*; 高橋 正光; 藤川 誠司; 神谷 格*; 大下 祥雄*; 山口 真史*

Journal of Crystal Growth, 323(1), p.13 - 16, 2011/05

 被引用回数:19 パーセンタイル:82.58(Crystallography)

In$$_{0.12}$$Ga$$_{0.88}$$As/GaAs(001)の分子線エピタキシャル成長中のひずみ緩和の様子をその場X線逆格子マッピングにより解析した。成長温度420, 445, 477$$^{circ}$$Cにおける残留ひずみ・結晶性の変化の様子が測定された。Dodson-Tsaoの運動学的モデルは、実験による残留ひずみの測定結果とよく一致することがわかった。さらにひずみ緩和過程における転位の運動の温度依存性の解析から、転位の運動の熱励起を議論することが可能になった。


Spins and parities of astrophysically important $$^{30}$$S states from $$^{28}$$Si($$^{3}$$He, $$n$$$$gamma$$)$$^{30}$$S

Setoodehnia, K.*; Chen, A. A.*; 小松原 哲郎*; 久保野 茂*; Binh, D. N.*; Carpino, J. F.*; Chen, J.*; 橋本 尚志*; 早川 岳人; 石橋 陽子*; et al.

Physical Review C, 83(1), p.018803_1 - 018803_4, 2011/01

 被引用回数:12 パーセンタイル:61.49(Physics, Nuclear)

$$^{30}$$Sの陽子が非束縛な状態は、古典的な新星爆発やI型X線バーストにおける水素爆発の温度での$$^{29}$$P($$p$$, $$gamma$$)$$^{30}$$S熱核反応率を強く影響する。特に、スピンとパリティが3$$^{+}$$と2$$^{+}$$の同定されている4.7から4.8MeVの励起エネルギーに存在する未観測の2つの状態が反応率に強く影響すると予言されている。最近の実験では、2つの候補の状態が4.699MeVと4.814MeVに観測されたが、実験的にはスピンとパリティの情報が得られていない。われわれは$$^{28}$$Si($$^{3}$$He, $$n$$$$gamma$$)$$^{30}$$S反応を用いて、$$^{30}$$Sのインビーム$$gamma$$線核分光を行った。スピンとパリティはよく知られているミラー核の状態との比較から同定した。


Real-time observation of anisotropic strain relaxation by three-dimensional reciprocal space mapping during InGaAs/GaAs(001) growth

鈴木 秀俊*; 佐々木 拓生*; 崔 炳久*; 大下 祥雄*; 神谷 格*; 山口 真史*; 高橋 正光; 藤川 誠司

Applied Physics Letters, 97(4), p.041906_1 - 041906_3, 2010/07

 被引用回数:32 パーセンタイル:75.54(Physics, Applied)

Real-time three-dimensional reciprocal space mapping measurement during In$$_{0.12}$$Ga$$_{0.88}$$As/GaAs(001) molecular beam epitaxial growth has been performed to investigate anisotropy in relaxation processes. Anisotropies, strain relaxation, and crystal quality in [110] and [1$$bar{1}$$0] directions were simultaneously evaluated via the position and broadness of 022 diffraction. In the small-thickness region, strain relaxation caused by $$alpha$$-dislocations is higher than that caused by $$beta$$-dislocations, and therefore crystal quality along [110] is worse than that along [1$$bar{1}$$0]. Rapid relaxation along both [110] and [1$$bar{1}$$0] directions occurs at almost the same thickness. After rapid relaxation, anisotropy in strain relaxation gradually decreases, whereas crystal quality along [1$$bar{1}$$0] direction, presumably due to $$beta$$-dislocations, becomes better that along [110] direction and the ratio does not decay with thickness.


In situ study of strain relaxation mechanisms during lattice-mismatched InGaAs/GaAs growth by X-ray reciprocal space mapping

佐々木 拓生*; 鈴木 秀俊*; 崔 炳久*; 高橋 正光; 藤川 誠司; 大下 祥雄*; 山口 真史*

Materials Research Society Symposium Proceedings, Vol.1268, 6 Pages, 2010/05

 被引用回数:0 パーセンタイル:0.01

The in situ X-ray reciprocal space mapping (in situ RSM) of symmetric diffraction measurements during lattice-mismatched InGaAs/GaAs(001) growth were performed to investigate the strain relaxation mechanisms. The evolution of the residual strain and crystal quality were obtained as a function of InGaAs film thickness. Based on the results, the correlation between the strain relaxation and the dislocations during the film growth were evaluated. As a result, film thickness ranges with different relaxation mechanisms were classified, and dominant dislocation behavior in each phase were deduced. From the data obtained in in situ measurements, the quantitative strain relaxation models were proposed based on a dislocation kinetic model developed by Dodson and Tsao. Good agreement between the in situ data and the model ensured the validity of the dominant dislocation behavior deduced from the present study.


${it In situ}$ real-time X-Ray reciprocal space mapping during InGaAs/GaAs growth for understanding strain relaxation mechanisms

佐々木 拓生*; 鈴木 秀俊*; 崔 炳久*; Lee, J.-H.*; 高橋 正光; 藤川 誠司; 新船 幸二*; 神谷 格*; 大下 祥雄*; 山口 真史*

Applied Physics Express, 2, p.085501_1 - 085501_3, 2009/07

 被引用回数:34 パーセンタイル:76.4(Physics, Applied)

${it In situ}$ real-time X-ray diffraction measurements during In$$_{0.12}$$Ga$$_{0.88}$$As/GaAs(001) epitaxial growth are performed for the first time to understand the strain relaxation mechanisms in a lattice-mismatched system. The high resolution reciprocal space maps of 004 diffraction obtained at interval of 6.2 nm thickness enable transient behavior of residual strain and crystal quality to be observed simultaneously as a function of InGaAs film thickness. From the evolution of these data, five thickness ranges with different relaxation processes and these transition points are determined quantitatively, and the dominant dislocation behavior in each phase is deduced.


Observation of second decay chain from $$^{278}$$113

森田 浩介*; 森本 幸司*; 加治 大哉*; 秋山 隆宏*; 後藤 真一*; 羽場 宏光*; 井手口 栄治*; 鹿取 謙二*; 小浦 寛之; 菊永 英寿*; et al.

Journal of the Physical Society of Japan, 76(4), p.045001_1 - 045001_2, 2007/04

 被引用回数:195 パーセンタイル:97.43(Physics, Multidisciplinary)



Experiments on synthesis of the heaviest element at RIKEN

森田 浩介*; 森本 幸司*; 加治 大哉*; 秋山 隆宏*; 後藤 真一*; 羽場 宏光*; 井手口 栄治*; Kanungo, R.*; 鹿取 謙二*; 菊永 英寿*; et al.

AIP Conference Proceedings 891, p.3 - 9, 2007/03

理化学研究所の気体充填型反跳分離装置(GARIS)を用いて、最重原子核の生成及びその崩壊の一連の実験が実施された。本実験において得られた112番元素の同位体$$^{277}$$112及び113番元素の同位体$$^{278}$$113の実験結果について報告する。$$^{208}$$Pb($$^{70}$$Zn, n)反応により同位体$$^{277}$$112からの崩壊連鎖が2例確認され、これは以前ドイツのGSIのグループにより報告された$$^{277}$$112の生成と崩壊を再現、確認する結果となった。また、$$^{209}$$Bi($$^{70}$$Zn, n)反応を実施し、自発核分裂で終わる$$alpha$$崩壊連鎖を2例観測した。これは113番元素$$^{278}$$113及びその娘核である$$^{274}$$Rg, $$^{270}$$Mt, $$^{266}$$Bhそして$$^{262}$$Dbであると同定した。

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